In fact, the lack of replaceable batteries is now becoming a consumer safety issue. Every city has a bomb squad who can isolate and destroy potentially explosive materials. This type of issue can be sorted out much more quickly, and much more safely, by having people turn in flawed lithium batteries to the local bomb squad. Further, if the batteries were standard sizes then there would likely be replacement batteries…
My impression is that replaceable batteries limit the shapes, materials and engineering that can be used, reducing capacity while increasing weight and size. For example a replaceable battery must be safely handled by end users, shaped and placed so it can be easily removed, and its connection is limited to something quickly and easily utilized.